Re: UFS bad inode, mangled entry on Alder Lake-N(100)

Reply: Milan Obuch : "Re: UFS bad inode, mangled entry on Alder Lake-N(100)"
In reply to: Ian FREISLICH : "UFS bad inode, mangled entry on Alder Lake-N(100)"
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From: Yamagi <lists_at_yamagi.org>
Date: Mon, 27 Jan 2025 18:28:28 UTC

Hi,

sounds like the Alder Lakes PCID bug in N100 flavor. On the small cores 
the INVLPG instruction is broken, failing to flush all (global?) TLP 
entries leading to cache corruption. FreeBSD has a work around for that: 
  https://cgit.freebsd.org/src/commit/?id=cde70e312c3fde5b37a29be1dacb7fde9a45b94a

However that work around never fully solved the problem on the N100 
series. My own N100 board was never stable with PCID enabled and there 
are several other reports of the same problems. For example 
https://lists.freebsd.org/archives/freebsd-current/2023-August/004116.html

Since Linux went with disabling PCID all together on all Alder Lake and 
Raptor LAKE CPUs, I did the same by setting vm.pmap.pcid_enabled=0 in 
loader.conf. Since I did that the system is running fine.

The Linux commit  disabling PCID is here: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ae8373a5add4ea39f032563cf12a02946d1e3546

A microcode update might also help. I didn't test the updates released 
by Intel since early last year so I don't know for sure.


Regards,
Yamagi


Am 27.01.25 um 18:10 schrieb Ian FREISLICH:
 > I recently bought one of those mini-pc firewall devices (Topton 12th gen
 > N100 with 4x I226-V, 2x X520) and couldn't get it to install pkg or
 > buildkernel without getting a slew of these messages, inode number
 > changing and a panic shortly thereafter.
 >
 > kernel: /: bad dir ino 4567815 at offset 0: mangled entry
 >
 > I tried the FreeBSD-15.0-CURRENT-amd64-20250124 snapshot and 14.2-
 > RELEASE, both with and without journal, trim and softupdates in every
 > permitted permutation without success. The system has an NVME, but I
 > experience the same problem with the install on a microsd and different
 > known good NVME drive. Each time I had to reinstall because the
 > filesystem was so corrupted it wouldn't boot after a fsck.
 >
 > The system is now running fine with ZFS so I'm wondering if it's
 > silently corrupting the ZFS or if there's a bug in UFS2 that's tickled
 > by this CPU. I'll provide any debugging required.
 >
 > Ian
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-- 
Homepage: https://www.yamagi.org
Github:   https://github.com/yamagi
GPG:      0xeb1472e71d502515